Files
libdatachannel/src/impl/threadpool.hpp
2021-04-13 23:03:16 +02:00

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3.8 KiB
C++

/**
* Copyright (c) 2020 Paul-Louis Ageneau
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef RTC_IMPL_THREADPOOL_H
#define RTC_IMPL_THREADPOOL_H
#include "common.hpp"
#include "init.hpp"
#include "internals.hpp"
#include <chrono>
#include <condition_variable>
#include <deque>
#include <functional>
#include <future>
#include <memory>
#include <mutex>
#include <queue>
#include <stdexcept>
#include <thread>
#include <vector>
namespace rtc::impl {
template <class F, class... Args>
using invoke_future_t = std::future<std::invoke_result_t<std::decay_t<F>, std::decay_t<Args>...>>;
class ThreadPool final {
public:
using clock = std::chrono::steady_clock;
static ThreadPool &Instance();
ThreadPool(const ThreadPool &) = delete;
ThreadPool &operator=(const ThreadPool &) = delete;
ThreadPool(ThreadPool &&) = delete;
ThreadPool &operator=(ThreadPool &&) = delete;
int count() const;
void spawn(int count = 1);
void join();
void run();
bool runOne();
template <class F, class... Args>
auto enqueue(F &&f, Args &&...args) -> invoke_future_t<F, Args...>;
template <class F, class... Args>
auto schedule(clock::duration delay, F &&f, Args &&...args) -> invoke_future_t<F, Args...>;
template <class F, class... Args>
auto schedule(clock::time_point time, F &&f, Args &&...args) -> invoke_future_t<F, Args...>;
protected:
ThreadPool();
~ThreadPool();
std::function<void()> dequeue(); // returns null function if joining
std::vector<std::thread> mWorkers;
std::atomic<int> mBusyWorkers = 0;
std::atomic<bool> mJoining = false;
struct Task {
clock::time_point time;
std::function<void()> func;
bool operator>(const Task &other) const { return time > other.time; }
bool operator<(const Task &other) const { return time < other.time; }
};
std::priority_queue<Task, std::deque<Task>, std::greater<Task>> mTasks;
std::condition_variable mTasksCondition, mWaitingCondition;
mutable std::mutex mMutex, mWorkersMutex;
};
template <class F, class... Args>
auto ThreadPool::enqueue(F &&f, Args &&...args) -> invoke_future_t<F, Args...> {
return schedule(clock::now(), std::forward<F>(f), std::forward<Args>(args)...);
}
template <class F, class... Args>
auto ThreadPool::schedule(clock::duration delay, F &&f, Args &&...args)
-> invoke_future_t<F, Args...> {
return schedule(clock::now() + delay, std::forward<F>(f), std::forward<Args>(args)...);
}
template <class F, class... Args>
auto ThreadPool::schedule(clock::time_point time, F &&f, Args &&...args)
-> invoke_future_t<F, Args...> {
std::unique_lock lock(mMutex);
using R = std::invoke_result_t<std::decay_t<F>, std::decay_t<Args>...>;
auto bound = std::bind(std::forward<F>(f), std::forward<Args>(args)...);
auto task = std::make_shared<std::packaged_task<R()>>([bound = std::move(bound)]() mutable {
try {
return bound();
} catch (const std::exception &e) {
PLOG_WARNING << e.what();
throw;
}
});
std::future<R> result = task->get_future();
mTasks.push({time, [task = std::move(task), token = Init::Token()]() { return (*task)(); }});
mTasksCondition.notify_one();
return result;
}
} // namespace rtc::impl
#endif